Cosmetics and their use as decorative applications for the human body have been in existence for centuries and are used extensively throughout the world. A multibillion dollar industry, cosmetics perform many different functions from lipstick to eyeliner, facial creams, powders, highlighters and nail polishes or lacquers. Although they are used primarily by women, their use is extraordinary and has made many of the cosmetic producing and marketing firms very profitable endeavors.
The nail polish sector of the cosmetic industry is extremely competitive and new colors, combinations and variations thereof are constantly being introduced in an attempt by the formulator to get and hold onto a bigger piece of the market share. The scientific research that is poured into these endeavors is considerable and new products and/or brand names are continually being introduced.
Nail polishes are essentially comprised of pigments and/or dyes that are incorporated and suspended in various solvents and bases. They must also be stabilized in suspension since if during the shelf life of the product the pigments should float, settle, separate or striate the product's appearance will be adversely affected. Nail polishes should also be formulated so that the film formed thereby is tough and durable and adheres to the human nail and will not readily crack, chip, peel or splinter when worn. This toughness should last for an extended time as well so that the polish enamel is durable.
Nail enamels conventionally comprise a film forming component, which is frequently nitrocellulose, cellulose acetate butyrate, or a combination of one or both of those cellulosics with a polyurethane or other polymeric compound. Nail enamels have also traditionally included plasticizers, typically a phthalate such as dibutyl phthalate, or camphor, and have also typically included as an adhesion promoter, a polymeric component formed by the condensation polymerization of formaldehyde or other aldehyde, typically an aromatic sulfonamide-aldehyde condensation resin such as o, .rho.-toluene sulfonamide formaldehyde resin, or a polyester resin such as phthalic anhydride trimellitic anhydride/glycol copolymer.
It has very recently become desirable to produce a nail enamel with reduced amounts of phthalate and aldehyde (e.g., formaldehyde) condensation products, in order to alleviate concerns that some wearers may be sensitized to these compounds or uncondensed aldehyde in the nail enamel. It is also desirable to reduce any volatile components since the volatility results in a loss of the component through evaporation which causes variability in the performance of the nail enamel. However, attempts to formulate such nail enamels have encountered difficulties because the nail enamel's desired properties such as long wear, high gloss, resistance to chipping on the nail, and compatibility with other nail enamel ingredients, are sensitive to changes in the ingredients in the nail enamel and to changes in the amounts of those ingredients. Therefore, there is still a need for a nail enamel formulation exhibiting satisfactory properties and containing little or no phthalate and/or aldehyde condensation products.
The prior art concerning nail enamels and/or lacquers strives to provide a nail enamel that exhibits superior suspension and stability characteristics for long shelf life duration as well as a high gloss, brilliant color and sheen that won't chip or crack during use and will withstand household chemical and temperature environments.
U.S. Pat. No. 5,066,484 to Castrogiovanni et al discloses and claims a number of glycerol triesters useful as plasticizers in nail polish compositions. The formulation further comprises a film-forming component, a solvent, pigments and other optional compounds as is known in the art. U.S. Pat. No. 5,145,670 also to Castrogiovanni et al. discloses similar nail compositions comprised of glycerol triacetates and trioctanoates as the plasticizers of choice. U.S. Pat. No. 5,225,185 also to Castrogiovanni et al. similarly discloses novel nail lacquers in which the formulation is free of formaldehyde and phthalate and the plasticizer is comprised of a copolymer formed by the condensation polymerization of formaldehyde and/or other aldehyde, typically an aromatic sulfonamide-aldehyde condensation resin. U.S. Pat. No. 5,227,155 also to Castrogiovanni et al. discloses further improved nail lacquers with glycerol triacetylricinoleate and glycerol tribenzoate as the plasticizers.
U.S. Pat. No. 5,133,966 to Khamis discloses still further nail polish formulations comprising improved pigment suspension systems. More specifically, the suspensions comprise carboxylic acids and their salts with a resin carrier in a buffered coating process that allegedly yields a hydrophobic coating with increased dispersion characteristics. Surprisingly, these suspensions allegedly don't effect the uniform dispersion of the pigments or the gloss and color of the nail polish enamel. U.S. Pat. No. 5,174,996 to Weber et al. discloses nail enamels with improved floatation, migration and settlement characteristics. These improved features are achieved by coating the pigments with oxidized polyethylene.
None of the prior art nail polish compositions have been able to exhibit a high gloss, defined color, long wear and chip resistance and yet retain nail flexibility and adherence over extended periods of time. More specifically, none of the prior art formulations achieve this goal while at the same time providing a phthalate-free plasticizer that, during wear, retains its durability and prevents the enamel from hardening and becoming more brittle which invariably results in the cracking and breaking of the nail coating.